Vobcopy will rip the dvd (into one big vob if you want).
It only takes 10 or 15 minutes as well. (maybe quicker)
Avidemux should be able to open the vob, from there click
on the "A Process" tab, then from the menu bar, Audio > Save Audio.
You can of course use Avidemux to cut out unwanted parts
before you save.
Vobcopy sometimes gets the A/V out of sync when ripping one big vob,
but that shouldn't matter for just saving audio.
http://vobcopy.org/
http://fixounet.free.fr/avidemux/